Process of making electric accumulator-plates.



N0. 703,420. Patented My 1902.

R, M. HUNTER. V i PBUGESS OF MAKING ELECTRIC ACGUMULATDR PLATES.(Application med Aug. 1, 1899.) (No Model.)

' FIG-8 UNITED STAT-Es PATENT OFF C RUDOLPH M. HUNTER, OFPHILADELPHIA,-PENNSYLVANIA.

PROCESS OF MAKING ELECTRIC ACCUMULATO R-PLATES.

SPECIFICATION forming part of Letters Patent No. 703,420, dated July 1,1902.

Application fiiealugusplsee. Serial No. 725,748. (roman) To all whom itmay concern:

Be it known thatl, RUD LPH M. HUNTER, of the city and county ofPhiladelphia, State of Pennsylvania, have invented an Improvement inElectrical Accumulators,of which the following is a specification.

My invention has reference ,to the manufacture 1' of electricalaccumulators; and it consists of certain improvements set out in thefollowing specification and typified inthe accompanying drawings, whichform a part thereof. g

My. invention setout. in this application (Case 309,) is especiallydirected to the manufacture of the positive plates of storage batteriesor electrical accumulators.

The object of my invention is to so construct an electrical accumulatoror storage-battery element that it shall possess great durability and avery low resistance.

By my invention I am enabled to cheaply construct the positive'platesand secure the best efficiency and longevity with a minimum weight. I

In storage batteries as heretofore constructed thepositiveplates havebeen made either as a groovedgridor kindred struc-' ture and subjectedto electrolyticaction to transform certain portionsof them into aperoxid of lead, or,else asagrid embodying openings or reticularformations which have been packed with a peroxid-of-lead com-v pound, orelse, again, as a cast grid provided with apertures which have beenfilled with; sheet-lead plugs driven in and subsequently rendered activeby electrolytic action. While the lastmentioned method of constructing apositive element for a secondary battery has mechanical advantages overthe two first mentioned with reference to manufacture-in its favor, yetno positive union between the active material and the grid results, andhence in timethe internal resistance becomes v abnormally high andaconsequent loss in effi--.

ciency ensues.

By my method of making thepositiveplate I secure thegreateststrength'with the least weight of material sufficient to insuredura bility, and, furthermore, obtain an absolute union between the bodymetal andlthe active material in the battery, in which the several partsmaking up the plate are assembled in process of manufacture.- p

In carrying out themanufacture of my improved battery-plate I first forma series of segments of spirally or otherwise folded or coiled strips ofsheet-lead, which I plage in a specially-constructed mold. Whileacooling medium, such as cold air, is drawn or forced through the coiledor folded strips of lead in the mold I cast about said strips orspeciallyprepared lead segments the lead 'body which is to unite withthem and cause them to constitute with the body a singlemechanicallyintegral structure or plate. The result of this operation isthat the hot fluidlead isnot permitted to fuse the coiled or foldedstrips except at their outer portions, Where it secures the formationbetween them and the body metal of an absolute fused joint,.whichreduces to a minimum the electrical resistance between thestripsandthebody metal of theplate and which no'amount of jarring orrough usage can destroy. The low inter- .nal electrical vresistar' ceisthus permanently insured. The platfes so constructed are then adapted,in selected numbers, connected by a bridge, to be built up in a positiveelement and tobe subjected to a forming process by the passage of acurrent of requisitestrength through the element until the surfaces ofthe coiled. or folded strips are converted into peroxidiof lead to thedesired depth. The element is then in condition for use.

As the interior portions of the lead-strips or segments retain theirmetallic condition, they act as an excellent conductor to convey thecurrent to the body metal of the plate,to which, as explained, saidstrips arefused or integrally connected. By shrinking the supporting orbody metal onto the segments which are to become active it is evidentthat, with or without also fusing said segments to the body of theplate, an-in ti mate andjclose union 'will be made 1. between ,saidbod-yandthe active material formed uponthe-segmcnts. Inasmuch as the segmentsare easily made and placed in the mold,

the operation of casting. and. shrinking the body metal upon-them isquickly and cheaply accomplished. Where the thickness of the strips isso great that they do not fuse in the casting of the body metal uponthem, the

passage of a cooling medium through them may be omitted. In fact, insuch case only the outer portions of strips need be thick, while thecentral portions may be relatively thin. In cases where the thickness ofthe strips guards them against bodily fusing without having to resort tothe use of the cooling medium their outer surfaces may be rough eued orabraded to form thin fusible projections which will fuse when the hotbody metal is forced into the mold and into contact with them. Thiswould insure a positive fused union between the segments and body metalin cases where thick strips are employed, thus securing the greatadvantage resulting from low internal resistance.

My invention will be better understood by reference to the accompanyingdrawings, in which- Figure 1 is an elevation of a completed plateconstituting a positive element of the battery and embodying myimprovements. Fig. 2 is an enlarged View of a portion of the plate ofFig. 1. Fig. 3 is a longitudinal section of the plate of Fig. 2 on theline 3 3 of said figure. Figs. 4 and 5 are diagrams showing othertypical shapes which may be given to the wound or folded strips of leadto become active. Figs. 6 and 7 are edge views of strips of leadconveniently used in the making of the segments of the plate. Fig. 8

is a sectional elevation of moldingapparatus conveniently adapted foruse in making my improved battery-plate; and Fig. 9 is an enlargedsection of a portion of the mold shown in Fig. 8, with the segments inplace and in condition to receive the molten lead.

A is the battery-plate complete, comprising the solid lead body-frame Band the segments 0 of active material or material adapted to becomeactive, as many of which are to be used as is consistent with thestrength of the frame 13. The segments 0 are each preferably formed of athin strip of lead coiled or folded upon itself, as shown in Figs. 2, 3,4, and 5, for example. The edge or perimeters of the segments may beconcaved, as indicated at E, so as to increase the hold of the leadframe upon them. The surfaces of the strips 0, of which the segments arecomposed, may be corrugated, serrated, or otherwise roughened, asindicated at C to obviate excessive density, to increase the surfaceadapted to become active, and also to present an exterior capable ofbecoming readily fused to unite with the metal of the bodyframe B in theoperation of casting. The outer portions of the strips may, if desired,be thinned, as shown at 0 Fig. 6, and also roughened on the surface, asindicated at C to secure more ready fusing of the perimeter of thesegment to the body metal.

For convenience in holding the Wound or folded segments intact withinthe mold and for preventing the cast lead from entering between thelayers of the segment at the end of the winding or folding the end maybe soldered, as at c, Fig. 4:.

In a preferred embodiment of my invention the lead frame B and the outerend of the segments are fused together, a result convenientlyaccomplished by employing a frail or readily-fusible outer end to thestrip secured either by reducing the mass of metal in the end of thestrip by roughening or abrading the end of the strip, or by doing both.This joiner of the parts to form an integral structure is shown in Fig.2, where the spiral strip is gradually blended into the metal composingthe body-frame B. As a result of this construction it is evident that bythe shrinking of the frame metal B upon the segments 0 the most intimatecontact will be secured, while by the fusing of said body metal to theouter circumferential portions of the segments the internal resistanceof the plate will be greatly reduced and its ellioiency consequentlyincreased.

Where a fused connection between the body-frame and the segments is wellestablished, an indented or depressed periphery to the latter isunnecessary. I prefer, however, to employ such indentation, as theaction of the dies in forming it will tend to solidify and strengthenthe central portion of the segment.

While in Figs. 1 and 2 I have shown the segments as circular andspirally wound, it is yet evident that they may be square, irregular, orpolygonal in outline, as typically indicated in Figs. 4 and 5. It isnot, moreover, as already stated, essential that the strips be woundspirally, as they may be folded or wrapped in any suitable manner tosecure the porous structure desired.

M, Figs. 8 and 9, is a mold in which to cast the lead body-frame B aboutand upon the segments 0. This mold conveniently consists of two parts orsections P and P, the opposing faces of which are conformed to receivethe segments and to leave about them spaces, as at R, into which to flowthe molten lead. The inner'faces of the mold-sections which respectivelyconfront the segments are provided with perforations or openings T,which communicate with chambers S S, respectively, within said sectionsand of which the chamber S is open to the atmosphere. The apertures Tare somewhat smaller'in diameter than the diameter of the segments, sothat the outer edges of the latter are clamped tightly down upon theinterior faces of the mold to make atight joint. The mold parts I P maybe clamped together by a suitable screw-clamp 0. When the mold partshave been supplied with the segments 0 and properly clamped together,the mold as a whole is conveniently placed upon an inclined table L, andan orifice through one of its sides, which communicates with themold-spaces R, is brought into contact with the nozzle K of a vat F andforced thereon, conveniently by um in the mold-chamber S air will becausedv to flow through the chamber S and between the layers of thesegments, soas to keep the.

central portions of said segments cool during the casting operation, andthereby prevent fusing, except as to the outer ends of the segments,which come into direct contact with the fluid lead and may be fusedintegral with the body of the frame B when cast uponthem. This fusing ofthe outer end portions of the segments to the body metal may bematerially facilitated by the employment of the roughened surfacesalready'referred to and indicated at C ,.Fi'g. 7.

The nozzle K connects by a pipe J with the bottomof a cylinder H,arranged within the lower part of a vat F, in which lead, with orwithout a given quantity of antimony, (and bismuth, if desired,) ismaintained in a fused condition by heat derived from a suitable furnaceG. 'Apiston or plunger I works within the cylinderH and when raisedexposes apertures h in the walls of said cylinder and permits the moltenlead to flow into it. When the plunger I descends, it forces the moltenlead up the pipe J into the spaces R of the mold, and thus thebody-frame B is cast about the segments under a pressure which willsecure density and perfectform. The pressure, moreover, insures closecontact of the molten metal with the outer edges of the segments, acontact which is increased by the shrinking whichtakes place when theplateoools. As this shrinkingaction of the body metal upon the segmentstakes place before any of the forming of the segments electrically is:resorted to, it is evident that the mechanical contactis excellent andliquid-tight, even where no fusing between the body and segment occurs.This shrinking action prior to the forming process in connection withthe manufacture of a battery-plate in themanner herein described is afeature of great importance, since it secures both strength and lowinternal resistance in the completed plate. After the plate has beenmadein the foregoing manner it is separately, or in conjunction with similarplates, placed in proper relation to a negative plate or plates in anelectrolyte of diluted sulfuric acid or other suitable oxidizing acidsolution, and a current of electricity ispassed through them for asuitable period to convert the surfaces of the metal of the segmentsinto the peroxid of lead. The plates thus prepared may then be employedin the usual manner in a storage battery, wi th the result that witheach charge the peroxid formation will be somewhat increased until intime every portion of the segments will have become active. In positiveplates for storage batteries thus formed the active material of thesegments will be so intimately connected with the body or frame that itwill retain during its life the low internal resistance even under themost severe strains of hard usage of the batteries, as in automobiles.

While the cooling of the segments during the casting operation is mostsatisfactorily accomplished by sucking cool air through them, it isevident that the air might be forced through them, or that instead ofair any gas or fluid may be used.

When the strips of which the segments are composed are sufficientlythick, they may be clamped tightly in place in the mold and the castingof the lead be accomplished without resort to the passage through thesegments of a cooling medium..

As already stated, the form into which the strips composing the segmentsmay be folded or wound is not essentialso long as the strips are causedto present an extended surface to the electrolyte. If desired, moreover,the segments may be mechanically made by casting or otherwise formingthem and be then placed in the mold and have the lead cast upon them,and therefore, although I prefer the construction by winding, I do notlimit myself to it or to kindred minordetails.

Having now described my invention, what I claim as new, and desire tosecure by Letters Patent, is-

1. The process of making an accumulator plate which consists in firstforming aseries of elementary parts with a large number of thin leadwalls, in then placing said elementary parts in a mold and clampingtheir outer edges tightly, in then passing a cooling medium through thecentral or interior portions of the elementary parts, in then forcingmolten lead into themold so as to cast it around the segments underpressure, and in finally transforming the surfaces of the thin walls ofthe segments into peroxidof lead.

2. The process for making a positive plate for an electrical accumulatorwhich consists in forming an elementary part of lead in light porouscondition, then placing saidelementary part in a mold and clamping theouter edges near the periphery tightly, then passing a cooling mediumthrough the central or interior portionof the elementary part, and whilethus cooled casting a lead body-plate about said elementary. part.

3. The herein-described method of making a positive plate for anelectricalaccumulator, which consists in forming a series of elementaryparts of lead with highly-fusible peripheries formed by wrapping orfoldinga lead strip upon itself, placing a seriesof said elementaryparts in a mold and shielding all-but their peripheries, positivelycooling the central portions of all of the elementary parts, casting abody of lead or lead alloyentirely IIO around and between the exposedperipheries of said elementary parts and by its heat fusing theperipheries alone of the elementary parts into an integral structurewith the body metal to make a close clean electrical connection, andfinally transforming those portionsof the surfaces of the segments notfused to the body into peroxid of lead.

4. The herein-described process of making a positive plate for anelectrical accumulator, which consists in forming a series of elementaryparts each presenting alarge number of thin lead walls wrapped upon eachother, placing said segments in a mold, retaining their central portionsonly in a cool condition, casting a lead body-plate entirely aroundtheir peripheral edges, fusing their outer peripheral edges to saidplate to constitute an integral structure, condensing the interiorlayers of the elementary parts upon each other by the cooling of thebody-plate, and finally subjecting the plate to an electrolytic actionto convert the outer surfaces of the thin lead ivals of the elementaryparts into peroxid of 5. The herein-described method of making apositive plate for an electrical accumulator, which consists in wrappingor folding a long strip of lead into elementary parts each having aseries of thin layers resting one upon the other, in placing saidelementary parts between the side walls of a mold of greater cubic,capacity then the mass of the elementary parts and making tight jointsbetween the exterior side circumferential edges of the elementary partsand the inside walls of the mold, and in finally filling the spacewithin the mold entirely around and between the circumferentialperipheries of the elementary parts with molten lead or its alloy andsolidifying the same before removal from the mold, whereby the shrinkingof the body metal condenses the layers of the elementary parts one uponthe other to greatly strengthen the finished plate and reduce theinternal electrical resistance when the plate is formed.

In testimony of which invention I have hereunto set my hand.

R. M. HUNTER.

\Vitnesses:

J. W. KENWORTHY, R. M. KELLY.

